The news follows weeks of confusion and controversy over his release, and a threat by his wife Elna to challenge the department in court if it did not set a date.
She said immediately after the announcement: "I am very, very excited. It is the happiest I've been for seven years. It was a long road we walked".
She was speaking ahead of a meeting with Goodwood prison officials - where her husband has been serving his sentence - to establish the exact time of his release.
Holding a dark blue suit, shirt and tie on a hanger, the clothes her husband will wear when he steps out of jail, Ms Boesak added: "I will not be happy until he is physically out".
Speaking earlier at a media briefing at the prison, provincial correctional services commissioner Mnikelwa Nxele said Boesak would be transferred to the correctional services office in Stellenbosch, where he would be released some time on Tuesday.
Asked to specify the time of the release, he said this decision would be made by officials at Goodwood prison, together with Boesak's family.
"We will leave it to them. During the course of the day, Dr Boesak will be transported to Stellenbosch, where necessary documentation with regard to his placement on parole will be handled by the (local) head of correctional services."
Parole conditions will confine Boesak
Nxele said conditions of the parole would confine Boesak to the Helderberg magisterial district.
"He needs permission to go outside this area. There is no requirement that he report to the police," Nxele said.
The release date follows an announcement last week by Western Cape director of public prosecutions Frank Kahn that Boesak would not be prosecuted over the stolen cellphone found in his possession in prison last year.
The phone issue had apparently been delaying a parole decision. Boesak appeared before the parole board in February and again at the beginning of May.
Nxele was on Friday instructed by his national office to "ensure a speedy resolution of this matter".
Denial under oath 'contrary to evidence'
In Thursday's statement, Kahn also said he had decided not to prosecute over Boesak's denial - on oath - that he had used the phone, which was "contrary to the evidence".
Nxele said on Monday: "Having considered all factors, including the investigation by director of public prosecutions Frank Kahn, the parole board of Goodwood prison came to the conclusion that no new facts came to the fore that have not been taken into account before.
"Therefore the management of the Western Cape correctional services decided to place Dr Allan Boesak on parole with effect from May 22."
Boesak began serving a three-year sentence for fraud from his former Foundation for Peace and Justice, on May 15 last year, and would normally have been eligible for parole after serving a third of his sentence.
The African National Congress welcomed the news of the release, saying it acknowledged the role the former anti-apartheid activist had played in the struggle.
"The circumstances that brought him to jail were very unfortunate and a part of our past," ANC media officer Nomfanelo Kota said in a statement on behalf of the organisation.
"We hope that his rehabilitation back into society will benefit not only his family but also the broader South African people."
Democratic Alliance correctional services spokesperson Hennie Smit said the DA accepted the parole board decision "provided there was no undue political interference in the decision-making process".
"We still want to know the full background of the stolen cellphone," he said. "This matter still hangs like a dark cloud over Allan Boesak."
Spokesperson for the South African Prisoners' Rights Organisation Luphert Chilwane said Sapohr applauded Boesak's challenging the department over inconsistencies in parole policy.
It would like the department to review the parole dates of all prisoners.
"We don't have any problem with his release, but we would like that to be something that benefits all prisoners," he said.